Backstory Horror is when something that seems harmless or is marketed as harmless has something horrible embedded in the Backstory. This backstory is Word of God - it's All There in the Manual in full horror for anyone who bothers to read. It's a fully intentional hidden well of Nightmare Fuel on the part of the creators, almost like a creepy Easter Egg for the fans. For example, let's say we have a story about fluffy bunnies, the story sets them out as being cute and cuddly good guys.